help with roll bar tech

[andy s]

From what little i can understand, DOM tubing at 1.5" O.D., weighs 1.426lbs at .095 wall thickness and about 1.73lbs at .120. So assuming a full cage, tied into 10 places will consume about 100 feet of tube, figure a 30-40 lb difference in cage weight.

So my question is what is the tensile strength difference in .095 vs .120 and is it material in regards to saftey or car flex

And what are the weights of Chrome-moly and compare the tensile strength of each.

If it's chrom-o, should it be 4130 or 3130? Or is there a better type of mix?

andy (who like Eric has a little to much time on his hands)

[Chuck Moreland]

My suggestion would be to look at the PCA or POC specifications for roll cages. The ground work you are trying to do has already been done, just follow their guidelines.

If you go Chromoly, go 4130.

[andy s]

Chuck;

thanks. I do already run SCCA and use a .095 Chromo cage in my car, but I am rebuilding my wife's race car. My questions are within the guidelines of options in SCCA. Based upon the weight of her car she can run either .095 or .120, AND either chromoly or DOM, so my questions are trying to determine what would be best for her car and what the real world differences are between the options.

Such as will using .120 make a material differences in the stiffness of the chassis? or is .095 more than enough?

4130 is a lighter and stronger metal than DOM (provided you re heat treat it after welding it), so will it make a material difference to use it? If .095 chromo is over 100lbs lighter than .120 DOM, and stronger, maybe a case can be made for using it, acknowleding that it is more expensive. (Althought .095 DOM is $1.80 a foot and .120 is $2.60..............

So i am trying to get more of a real world education on the differences

thanks

andy